(E,2E) SPECTROSCOPY - FROM ATOMS TO SOLIDS

In this paper we describe briefly the theory of (e,2e) spectroscopy of atoms and molecules. Subsequently we introduce a simple model for a one-dimensional crystal. We calculate the (e,2e) spectra as would be measured for this hypothetical case, and use this model to make a link between (e,2e) spectroscopy as applied to atoms and molecules and this technique as applied to solids. Slight modifications of the model allow for the simulation of the effects of different band structures on the (e,2e) spectra. Special attention is paid to the difference in the type of information obtained from (e,2e) spectroscopy and that obtained from angular resolved photoemission. Finally, we show qualitatively some results of (e,2e) spectroscopy of solids that corroborate the picture sketched.